Liquid shaft seal



July 11, 1944. H. E. LA BoUR 2,353,478

LIQUID SHAFT SEAL Original Filed March 17, 1939 2 Sheets-Sheet l `uly ll, 1944. H. E. LA BouR 2,353,478

LIQUID SHAFT SEAL Original Filed March 17. 1939 .2 Sheets-Sheet 2 `composition of the fluid mediums.

Patented Y UNITED' STATES PATENT. OFFICE l t l uoun'sssrsm A` 4 i i mllyE.L&Bdll!,Elkh&rf,Ind.

(9 Claims. (Cl. 286-9) My inventionvrelatesto liquid seals for shafts and the like. In various devices it is desirable to I extend a rotatable' shaft through a wall upon opposite sides of which it is desired to maintain a difference in pressure or a difference in the The present invention has general utility, but it has particular value in self-priming centrifugal pumps as will be apparent from the following specification. While I have illustrated the invention as embodied in a self-priming centrifugal pump, that is by way of illustration and I do not intend to limit the invention to the specific use nor to the details of the specific pump shown. Y

A liquid seal is desirable in a pump of this class, particularly when the shaft must operate at high speeds or when the liquid being handled is corrosive to the shaft surface or to the composition of the packing. y

In the use of a liquid shaft-seal it has been found that the liquid tends to be thrown away from the shaft by centrifugal force, thereby reducing the effectiveness of the seal. This is caused by the action of the water in adhering to the shaft upon contact with it, but being cast olf in a' tangential direction by the centrifugal force created by the whirling shaft. Then there is a tendency for a path for air to be formed along the shaft resulting in pressure breaking through" the weak liquid seal. For satisfactory operation, liquid must be constantly present and must completely fill the cross section of the gap between the shaft and the sleeve or casing.

According to the present invention, I have provided a novel method of compelling the liquid to 'remain in engagement with the shaft and cornpletely fill the cross section of the gap between the shaft and the surrounding sleeve, or casing elements at one or more points, thus satisfactorily overcoming the usual action caused by the centrifugal force of the rotating shaft, This desired result is obtained` by introducing liquid through ports into the gap between the shaft and sleeve or casing in a direction tangential to the direction of rotation of the shaft. 'I'he entering liquid, in passing into the gap, is forced into narrow converging passageways formed between the walls of the above mentioned ports and the shaft. The rotating shaft also tends to drag the liquid by adhesion and cohesion through these passageways. The restriction thus offered to the liquids flow by the narrow passageways causes it to be squeezed and consequentially to seek escape. The

only other path open to it is upward and downshaft and the sleeve or casing. InV escaping from the restricted passageways the liquid is so squeezed or forced that it spreads throughout the full cross section of the gap, i. e., completely about the shaft, for a limited but sufficient distance both above and below theA entry ports. Of

these two sealed areas in the gap it is the seal between the enclosed chamber and the entry port which is most important, for thoughthe other sealed area would prevent pressure breaking through along the shaft, it would not preventv any pressure break-through which might come along the ventrance passage of the liquid itself.

The pump herein illustrated and described, to show a practical application of the seal. is suitable for and intended to be operated at speeds of the order of 2400 to 3600.R. P. M., and can be operated at higher speeds if necessary. 'Under such speeds, the problem of centrifugal force and diminishing of the pressure of the sealing liquid Y at the surface of the shaft becomes acute. I-Iowever, the invention is not limited to pumps of high shaft speed, as the advantages appear at all practicable lpump speeds and in uses other than ,in Dumps.

` cannot, under any circumstances, rise into the bearings o r driving means of the shaft must be had, and to solve this difficulty appropriate disposal means have been provided as will appear more fully hereinafter.

Though my liquid shaft seal is hereinafter described in conjunction with a self-priming centrifugal pump, this is in no way to be considered a limitation upon the scope of my invention, for it is readily adaptable to other devices and uses.

In the accompanying drawings, which form a part of the present specification and in which like reference numerals refer to like parts,

Figure 1 is a vertical section along the lines l-I of Figure 2,- through a self-priming centrifugal pump employing my iiquid shaft seal;

ward along the shaft in the gap between the II FigureZisacrossFsectional view along the lines body casting I.

2 assaus 1 along the shaft.

The present application is divisional of my copending application Serial No. 262,339. filed `March 17, 1939, now Patent No. 2,297,001,1issued September 29, 1942, `to which reference may be had for a full disclosure of the operation of the pump as a' self-priming centrifugal pump as such.

The self-priming centrifugal pump in which my liquid shaft seal is employed comprises the following main parts: a main body casting I, an impeller 2, an impeller housing plate 3, and a closure plate 4 which forms not only a closurel for the main -body castingI I but also completes the impeller housing for the impeller 2. A bearing bracket-5 which supports the impeller shaft 6 is mounted on the upper portion of the main The bearing bracket is connected to the motor-frame (not shown) and it carries an antifriction bearing houbsing 5' for supporting the shaft l.

The above described parts define three main coaxial chambers, namely, the impeller chamoer 1, the discharge chamber 9, and an inlet chamber '9 through the longitudinal center of which passes the impeller shaft 6 with its liquid seal. An outlet passageway I0 communicates with the chamber 8, and an inlet passageway (at the opposite side of the pump from duct I6 and in line with the same and therefore, not shown) communicates with the inlet chamber 9. During priming the discharge chamber 6 serves as a gas and liquid separator. It serves also as a trap to retain liquid when the pump stops. Chamber 8 surrounds the impeller chamber VI and communicates therewith by pairs of throats 29 and l0. Inlet chamber 9 communicates with the impeller chamber 'I through the eye or inlet opening I2. Throats 29 discharge tangentially into the separator 8. During priming, throats 90 provide a return flow from the separator 8 to the impeller housing I and then, after priming, serve as auxiliary outlets from the impeller housing into the discharge chamber (separator) 8.

I shall now describe the liquid shaft seal in coniunction'with the above structure. There is a tubular extension 2| formed integrally with the main body casing I which provides a barrel vfor housing a liquid seal sleeve 22 which surrounds the shaft 5. This barrel 2| is divided passageways. The walls of the Vtu-bular inlet passageway 56 extend out to the outer peripheral wall I9, where an opening is provided which permits inspection and cleaning of the duct 56. This opening is normally closed by the pipe plug y 58. A similar opening through the wall I3 supply chamber than can be used in the liq-l by an inwardly extending flange wall 23 into two functionally separate chambers, namely, the upper or drain chamber 24 and the lower or liquid supply chamber 25. A suitable packing 26, disposed in an annular pocket or recess in flange 28, tends to maintain a substantially tight joint with the sleeve 22 so as to seal off the two chambers 24 and 25 from each other. Absolute tightness at this joint is not essential.

The lower chamber 25, which is a liquid supl ply chamber for the liquid shaft seal, is provided with two adjacent ducts 56 and 51 (see Figure 2) the walls of which may be formed integral with the main body casting as by forming cored there are in the sleeve 22 a series of slots or (shown in Figure 1) above the`pipe plug 58 is closed by a pipe plug 59. This opening 60 is for initially filling the pump for operation.

The supply passageway 56 opens downwardly at the opening 62, so that the duct may be supplied with liquid even at a minimum of liquid level in the separator space 8. The direction of opening is optional. The opening 62 is substantially non-clogging and it opens at the point where the liquid is densest and, during priming, hasthe maximum swirl. in the separator 8 tends to keep the entry port 62 clear. Since the size of the duct 56 is of such a diameter as to feed more liquid to the liquid uid shaft seal, the passageway 51 is provided as a liquid overflow or return passageway from the liquid supply chamber surrounding the sleeve 22. 'I'he supplying of this excess of liquid for the seal is desirable and not a wasteful action vsince it prevents a shortage of sealing liquid and consequent possible .break through of pressure. It keeps pocket l25 fullof liquidy and tends to prevent sediment settling in the pocket.

'Ihe liquid sealing sleeve is provided with an annular shoulder 63 at its lower end, and this ange is drawn against the bottom wall of the tubular extension 2I to form a. tight connection by means of the threads at the upper end of the sleeve 22, these threads 64 being engaged by the nut 65, which nut has engagement with the bottom wall of a pocket 2l to hold the sleeve 22 in place. The nut 651s internally channeled at 66 to cooperate with the slinger ring 61 which is I slipped onto the upper end of the shaft 6. The

nut 65 has openings 68 by which any liquid thrown olf by the slinger ring may drain into the bottom of the pocket 21 and thence flow to the outside of the main Ibody casing I through an open trough or channel 39 to the opening 46 and be conducted oil through the drain pipel 44.

The sleeve 22 forms a tight joint with the lower wall oi the tubular extension 2I as by means of a flanged head 63, and it forms a substantially tight connection with the flange 23 by virtue of the packing 26 above described, so that the liquid supply chamber 25, which is put under discharge pressure when the pump operates to pumpliquid, will be substantially liquid tight. Obviously, -the details of securing the parts' together and of securing the tight relationship above referred to may, optionally, be varied.

The sleeve 22 is bored to t the shaft 6 without gripping it. That is to say, there is aI small clearance between the bore of the sleeve 22 and the shaft 6. 'Ihis clearance is a small annular gap winch is made so small as to constitute a material restriction to liquid flow but which would not exclude entry of gas or air if no sealing liquid were supplied. A few thousandths of an inch clearance may be provided, depending upon the character of the liquid to be pumped, the entrained solids, etc. Near its upper end, and regis- ^tering with the discharge or overilow pocket 24,

windows 'I0 and the inside of the bore is relieved at these windows 10. Any liquid coming along the shaft 6 and entering the relief pocket 'l at the windows I0 is free to ow outward radially l The swirling of liquid l assaus ma the chamber or pocket u in the tubular extension 2l and to escape to waste lthroughthe tube Il and the pipe Il. Liquid tending to creep upwardly along "the shaft 5 past the relief pocket 24 and windows 'I5 must pass, first, the restricted gap in the upper end cf the sleeve and 4 then it wm encounter the slinger' ring t1. where it will be thrown ofi' within the surroundingslinger groove 55 inthe nut 55.

` Within the supply pocket 25 the sleeve 22 hasv a relief groove 12 communicating with the windows I'IIJ A shallow relief groove 'I3 may be cut in register with the inlet passageways 15. groove is optional. communicates with a series of tangential inlet passageways 'I5 (see Figures 2 and 3) which permit liquid to come into contact with the shaft, moving substantially tangentially in the direction of rotation of the shaft 5. The liquid contacting the shaft adheres thereto momentarily and is 'I'his The lower supply-groove 15 gap between the shaft 5 and the sleeve 22.v both' in an upwardly and lin a downwardly direction from the region of the ports 15 which thereby dragged, by rotation of the shaft, into a narrow- 1 ing space provided by the inclined walls 90 of .the passageways 'l5v which lead the liquid against sageways constitute, in effect,v a small multiple pump, forcing liquid inwardly into engagement with the cylindrical surface of the shaft and providing an excess of pressure at the surface of the shaft which helps form a very effective seal. The plenum of liquid pressure along the surface of the shaft produced by this arrangement makes it possible to provide a relatively short liquid seal of great effectiveness. Heretofore, attempts to seal with liquid have encountered the marked difllculty of maintaining the liquid in firm contact with the surface of the shaft all the way around it because of the centrifugal effect of the shaft in throwing the liquid away from itself. The higher the speed, the greater has been the tendency to discharge the liquid away from the shaft, and suction would tend to strike down along the shaft even though liquid were supplied in abundance.

This can be seen particularly if the shaft is slightly eccentric with respect to the surrounding sleeve with which a liquid seal is to be maintained, for there would be a crescent-shaped lacuna or passageway left open between the shaft and the rotating liquid in the sleeve if there were any lack of concentricity between the two.

In the arrangement which I have shown (see particularly FigureZ), the higher the speed of` the shaft the greater the velocity effect which occurs in driving the liquid into the narrowing space between the wedge-shaped part of the sleeve and the surface of the shaft.

Now the wedging action of liquid ateach of the inclined vanes produces a longitudinally extending area of positive liquid pressure. This pressure tends to act in all directions (Pascals law), and since it is restrained circumferentially of the shaft it tends to force liquid endwise into the gap. 'I'liese ports and their inclined spaces are close enough to each other and have an effect suillcientlyfar in circumferential direction to produce the effect of a complete circumferential ring of pressure at both the upper and the lower ends of the ports 15. That is to say, in

effect there is a pumpforcing liquid into the .produces the two desired positive liquid sealing rings'between the sleeve 22 and the impeller shaft 5. v

Since this pumping effect produces a plenum of pressure `at the surface of the shaft, there is" a tendency for liquid to be discharged longitudif nally along the shaftfthrough the clearance.

Any downward discharge returns to the inlet chamber 9 where it will be put back into serv- 4ice again. In order to avoid an excess of discharge along the shaft in the upward direction, where it would be wasted, I have provided, at a point slightly above this liquid wedging arrangement. the reliefA windows 'll which permit excess pressure at the surface of the shaft. to be relieved and to flow back into the liquidl supply pocket 25. Obviously this latter is an expedient which, while advantageous, is not essential f' to securing the wedging action against the surface of the shaft for producing the sealing effect.

A restriction against free escape of liquid in the upward direction -is needed to get the maximum downward pressure.

The arrangement above described may obviously be varied in detail, but the wedging of the liquid against the shaft around the same has proven highly effective, and maximum suction which the pump may attain vby virtue of its `pumping and self-priming action-is unable to produce any gas leakage along the shaft. I therefore consider the abovefnovel arrangement of forcing liquid against the surface of the shaft to provide a liquid seal to be of importance, andAv a marked advance in the art.

It will be observed that I have disposed the liquid sealing sleeve at as low a point as possible along the shaft length 5. It is desirable to have the liquid flow by gravity into thesupply cham` I0 ports 15 and the sealing portion of the sleeve below said ports 15, is disposed below the normal ltrapped level of liquid in the pump when the pump stops. I [t is to be observed that as soon as the impeller is rotated the liquid is withdrawn from the trap and discharged into the separator. This raises the level in the separator and produces a swirling of liquid in the separator, producing dynamic separation of gas from the liquid, and insuring that the level will be above the bottom of the ports 15, so that a liquid seal may be maintained on the lower end of the sleeve. For best results, the liquid should be at a high enough head to insure filling the ports 15 and then the pumping effect 4of the shaft 6 and said ports 15 is insured. In earlier forms of this seal I have faced the inlet opening 52 for the inlet passageway horizontally against the direction of rotation or swirl of liquid in the separator, so as to cause 'lo f mit liquid pressure to the chamber 25. However,

vthat construction has a greater tendency to conan impacting'of the moving Aliquid upon said opening.A It then acts as a pitot tube to transto the walls 90 and the shaft 6. The indicated path of this particle M is a representation of the action of the mass of the liquid forming the seal. Th'e particle M enters the supply chamber 25 afteriiowing up the supply duct 56 (as described in Fig. 1) because the rotation of the shaft 8 and impeller 2 has sent the particle M into and along this duct 56 with the other particles that form the mass of liquid. From the supply chamber 25 the particle M enters one of the ports 15 and continues along the path indicated by the line and arrow heads cf Fig'. 3. Its first contact is with the shaft 6 which is rotating in a clockwise direction. It adheres to the surface of the shaft momentarily but is almost immediately cast oif from the shaftin a tangential direction whereupon it im-pinges upon one of the walls 90. The

angle of rebound from the wall is equal to thek angle of incidence. The particle M comes in contactv with the shaft 6 again, and is again. cast off tangentially to a second wall 90 whereupon the rebounding and subsequent tangential throws continue to pass the particle all around the shaft.

.It is to be noted that particle M is squeezed or dragged through the small gaps between the shaft 6 and walls 90 along with other particles. These particles, it may be assumed, entered the ports 15 but were subsequently crowded through thevsmall gaps which are many times smaller than the size of the entry ports. This causes the liquid pressure 'against the shaft, which we have spoken of above.`v Of course. the pressure against the shaft is less between the narrowgaps than right at them, but this does not allow any break through of Apressure as I shall now explain.`

Inaddition to the action of the shaft `5 in driving and wedging the liquid against itself, the

filled with liquid under pressure at the region of the approach of inclined surfaces 90 to the surface of the shaft 6, the liquid is forced longitudinally of the'shaft at these regions of pressure into the annular gap between the vshaft 6 and sleeve 22 both above and below that portion of the sleeve 22 which houses the entry ports 15.

Figure 4 indicates diagrammatically a vertical cross section along .the lines l-l of Figure 3, and shows this liquid seal 99 above and below the entry ports and between the shaft 6 and sleeve 22. The crests on this liquid s eal tend to occur above and below the narrow gaps between the walls 90 and shaft 6 where the liquid is squeezed the most. The fact that the liquid spreads in all directions when squeezed, accounts for the complete ring of sealing liquid between the shaft and sleeve above and below the entry ports 15 which thus excludesa break-through vof pressure into the impeller chamber.

It may be noted that concentricity of the shaft and sleeve is desirable but not essential.

Now I have described the liquid shaft seal in a self-priming centrifugal pump where the shaft Ainstala ofy vertical; other suitable liquid supply means could be used; there would not need to be a lconstantly present supply of trapped liquid around one end of the shaft since the supplying of liquid could begin before, at or after the starting of the shaft for service; Vand many other adaptations and changes could be made without departing from the spirit or scope of my. invention as is outlined in the appended claims.

I claim: v

1. A liquid shaft seal comprising a shaft, a

. sleeve embracing but not fitting against said shaft, said sleeve comprising a plurality of entry ports for introducing liquid into engagement with the surface 4of the'shaft, said shaft and each of said ports providing atapering space into which the friction of the shaft with the liquid dragsthe liquid in the direction of rotation of the shaft into wedging engagement between a part of the sleeve and the shaft. f

2. vA liquid shaft seal comprising a shaft, a sleeve embracing but not fitting against said shaft, said sleeve comprising a, plurality of ventry ports forintroducing liquid into engagement with the surface of the shaft, said shaft Aand each of said ports providing a tapering space intd which the friction of the shaft with the `liquid drags the liquid in the direction of rotation of the shaft into wedging engagement. between a part of the sleeve and the shaft, and entry and exit ducts cooperlating with said sleeve to provide a circulation of liquid to and from the part of the sleeve having saidentry ports.

3. A liquid seal for a shaft comprising a barrel surrounding the shaft and having an intermediate annular web dividing the inside of the barrel v into upper and lower chambers, a sealing sleeve seated in the bore of the barrel, said sleeve being adapted to embrace but notgrip the shaft to be sealed, ducts connected to said chambers for supplying and evacuating sealing, liquid, said sleeve having a series of liquid supply passages lying in a common transverse plane, said passages having walls .extending substantially tangent to f. the inner bore whereby liquid by its frictional engagement with the shaft is dragged in the n direction ofrotation of the shaft into wedging is Vertical and where the level of the`liquid is so 1 engagement between the shaft and the sleeve.

4. A liquid seal for a shaft'comprsing a barrel surrounding the shaft and having an intermediate annular web dividing the inside of the barrel into upper and lower chambers, a sealing sleeve seated in the bore of the barrel, said sleeve being adapted to embrace but not grip the shaft to be sealed, ducts connected to said chambers for supplying and evacuating sealing liquid, said sleeve .having a series of liquid supply passages lying in a common transvese plane, said passages having walls extending substantially tangent to the 'inner bore whereby liquid by itsv frictional engagement with the shaft is dragged in the direction of rotation of the shaftinto wedging engagement between theshaft and the sleeve, there being liquid relief ports between the inside of the`sleeve anda part of the same chamber in which said liquid supplying passages lie to prevent the forcing of'lquid toward the free end of the sleeve.

5. In combination, ashaft, a closed chamber having a Wall through which said shaft passes and to which it is to be sealed, a barrel joined to said wall, a sealing sleeve supported in said barrel, said sleeve embracing but not gripping said shaft, said barrel forming a chamber about a portion of the sleeve, said sleeve having ports with walls substantially tangential to the surface of the shaft, said ports opening at their outer ends into said chamber and at their inner ends into the space between the shaft and the bore of the sleeve, said shaft upon rotation tending to drag liquid in the direction of the rotation of the shaft into wedging engagement between the shaft and the wall of the sleeve, and means to admit liquid to the chamber, one end of the sleeve opening inside the aforesaid wall and the other end opening outside the wall. y

6. In combination, a shaft, a closed chamber having a wall through which said shaft passes and towhich it is to be sealed, a barrel joined to said wall, a sealing sleeve supported in said barrel, said sleeve embracing but not gripping said shaft, said barrel forming a liquid supply chamber about a portion of the sleeve, said sleeve having ports with wallsl substantially tangential to the surface of the shaft, said ports opening at their outer ends into said latter chamber and at their inner ends into the space between the shaft and the bore of the sleeve, said shaft upon rotation tending to drag liquid in the direction of rotation of the shaft into wedging engagement between the shaft and the wall of the sleeve, means to admit liquid to the supply chamber, one end of the sleeve opening inside the aforesaid ,wall into the closed chamber and the other end opening outside the wall, said barrel providing a discharge chamber inside the 4aforesaid walladiacent the the bore of the sleeve, said shaft upon rotation tending to drag liquid in the direction of rotation of the shaft into Wedging engagement between the shaft and the wall of the sleeve, and means to admit liquid to the chamberfone end of the sleeve opening inside the aforesaid Wall and the other end opening outside thewall.

8. In a liquid shaft seal suitable for excluding air from the intake side of a, centrifugal pump, the combination of a vertical impeller shaft, and a sleeve adapted to communicate at its inner end with the suction side of the impeller, said sleeve embracing but not fitting against said shaft, said sleeve comprising a, passageway for introducing liquid into engagement with the shaft, said shaft and said passageway providing a tapering space between them into which tapering space the shaft drives the liquid into wedging engagement between an adjacent part of the sleeve and the shaft by the drag of the shaft upon the liquid in the direction of rotation of the shaft.

9. In a liquid shaft seal suitable for excluding air from the intake side of a centrifugal pump. the combination of a vertical impeller shaft, a sleeve adapted to communicate at its inner end with the suction side of the impeller, said sleeve embracing but not fitting against said shaft, said sleeve having an opening intermediate its ends for introducing liquid into engagement with the shaft, said shaft and the walls of said opening poviding a tapering space between them into which tapering space the shaft drives the liquid in the direction of rotation of the shaft into wedging engagement between a part of the sleeve and the shaft, and entry and exit ducts cooperating with said sleeve to provide a. circulation of liquid to and from the part of the sleeve having said opening. HARRY E LA HOUR. 

